Why Your Clematis is Not Blooming and How to Get it to Flower

Why Isn’t My Clematis Blooming?

Okay, let’s jump right in.

You’ve got a clematis vine, it’s growing new leaves and stems, but there are no signs of buds or flowers.

Because the plant appears healthy, it’s probably not a disease or poor growing conditions, so what’s the problem?

To find the answer, I read a lot of advice from various clematis experts around the web and here’s what I found.

There’s 5 basic things (or a combination of them) that could be preventing your clematis from flowering.

1  Improper Pruning

Pruning plants is both an art and a science. We prune for the welfare of the plant and our own aesthetics.

With clematis, you really need to know what you’re doing because it’s easy to accidentally remove stems that would have provided flowers.

To prune properly, the first step one is to know which type of clematis you have.

Clematis are generally divided into Types/Groups 1, 2, and 3.

Bloom times and whether the flowers form on new or old growth determines when, if, and what you should prune.

Types of Clematis (species and hybrids)

• Type/Group 1: Produce spring flowers on previous year’s growth.
• Type/Group 2: Late spring/early summer blooms on old growth, may also bloom in fall on new growth.
• Type/Group 3: Blooms in summer and early fall on new growth.

There are also herbaceous clematis that die back and regrow each year, and they are fine with a deep pruning after blooming. 

It’s the Group 1 and 2 clematis that bloom on old growth that are often victims of improper pruning. These guys produce their flowers on the previous year’s growth, and many gardeners like to ‘tidy up’ the fall garden by cutting back plants like this. Don’t do it! You may very well have removed everything that would have provided this year’s blooms.

How to ID your clematis without flowers

You might not be able to! Flower appearance and timing are the best clues for identifying clematis. Leaves and stems are also key, but I don’t think it can be done without some clue about the flowers as well.

So, you may be out of luck until you get it blooming, which is another reason to hold off any pruning. The tips below may be just what you need.

If you want more growing info, this article has basic info on types of clematis, pruning schedules, and resources for identifying your clematis type (by colour and blooming time).

2 Nutrient Imbalance

Do you fertilize your clematis? If so, what fertilizer do you use? 

If your clematis is healthy and growing but does not have flowers, it could be an issue with the soil, specifically a nitrogen imbalance.

Check the label on your fertilizer.

Fertilizers are labelled to show the main macronutrients: nitrogen (N), phosphorus (P), and potassium (K) in (what we call) percentages*.

*These are not all true percentages but we have adopted this way of explaining it to keep it simple. If you want to know what’s really going on, this entry at Wikipedia describes it.

Excessive nitrogen may be the problem with your non-flowering clematis because this nutrient stimulates leafy green growth, sometimes at the expense of flowering.

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One recommended fertilizer for clematis is Espoma Rose and Flower Food (4-3-2), which is an organic, slow-release fertilizer.

To keep things simple, we say it contains 4% nitrogen (N), 3% phosphorus (P), and 2% potassium (K). While these aren’t the true percentages for the phosphorus or potassium (they have a different calculation), it’s good enough to know these numbers for home gardeners to choose the right fertilizer product.

With it’s 4-3-2 formula, Rose-tone is not too high in nitrogen, making it suitable for boosting flowers in roses and clematis and other flowering plants. There are also fertilizers marketed for home tomato growers with similar properties.

All-purpose fertilizers are often too high in nitrogen for flower production. The N-P-K ‘percentages’ may be 10 to 20 or higher. This may be good for specific green growth, but not blooms.

In general, clematis experts recommend a low-nitrogen, steady, slow-release, organic fertilizer throughout the growing season. Always follow the instructions on the product label to get volumes right: too much can harm or kill your plants and wreck your soil.

If you’ve been using the wrong fertilizer, stop. If possible replace some of the soil around the plant (and careful where you dispose of it or it may negatively affect other plants), and ease into a new fertilizing schedule with the right product.

Lots of green growth without fertilizers

If you have not added anything to soil, but you have an abundance of green growth on the clematis without flowers, it would be worthwhile to get a proper soil test done to analyze your soil and receive recommendations on how to organically improve it to support flower growth.

Here in  Ontario, Canada there are plenty of labs that will analyze soil (link below). You may be lucky enough to have a university extension office or other conservation authority that will do this for you for a nominal fee.

The Lime Myth

On a side note, there is an old, popular myth that clematis like lime (which makes soil alkaline) and some gardeners routinely add lime around the base of their clematis plants each spring. We know now that this is not true or beneficial. Clematis actually prefer slightly acidic soil in the pH range of 6.2 to 6.8, so no lime required!

Summary of Fertilizer Problems & Solutions

• If you’re using the wrong fertilizer, you can correct this moving forward by using the right product as directed (e.g. Espoma Rose and Flower Food (4-3-2).
• If you haven’t had your soil tested, consider doing this as it can be highly informative for a variety of gardening decisions.
• Never add amendments (like fertilizers or any other products) unless you know they are truly needed, beneficial, and cause no harm.

For other plant types see the Beginner’s Guide to Organic Fertilizers for the Home Garden.

3 Inadequate Light

Is your clematis getting adequate light?

Clematis can grow in partial shade, but, overall, they perform best with at least 6 hours of sun or bright shade a day.

A shady location may delay growth and flowering.

Transplanting to a better location may be required.

Get a Clematis Resource Guide

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4 Too Young to Bloom

This is a point a few clematis growers online have mentioned that had not occurred to me. If your clematis is fairly new (under 3 years old), appears healthy, yet produces just a few blooms, this can be normal, assuming productive stems have not been pruned away.

As the plant ages, the roots grow, giving the clematis a greater ability to produce more shoots and blooms.

In other woods, give the kid some time to grow up. It may be just fine next year.

5 You Got a Dud

It happens to all of us!

Sometimes, when you’ve exhausted all possibilities, it comes down to the fact that some plants are duds.

In my garden, if the plant is otherwise healthy but just not giving what it should, I may designate it to a less prominent place in the garden.

If it was purchased with a guarantee, I may return it to the nursery.

If it’s struggling or suspect, I dispose of it.

I’d rather move on than fuss over a weak or lackluster plant.

Summary

If your clematis is adding a lot of green growth with no sign of flowers:

Check your fertilizer. Be sure to use one with a low percentage of nitrogen.

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Get your soil tested. There may be an imbalance or deficiencies you can improve organically.

Did the clematis bloom in previous years?

If so, what changed?

Was it improperly pruned?

Did you change fertilizers?

Is there adequate light?

Is it a young plant and needs time to mature?

Or, might you have a dud?

I hope you solve the problem and have a flowerful future.

~Melissa the Empress of Dirt ♛

More Clematis Tips

• Clematis 101 | Easy Care Guide – Identify and Prune
• How to Grow Clematis from Cuttings | Home propagation
• A Way to Garden | Margaret interviews Dan Long, Clematis Expert
• Clematis Queen | More clematis growing information 
• Index of Clematis Tips | For growing, propagating, and troubleshooting

Soil Testing

• Ontario, Canada | Soil Testing Labs
• United States | Ask at your university extension office for recommended labs

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